1. Field of the Invention
The present invention relates to an indexing apparatus which is adapted to convert a continuously rotating input power available from a conventional prime mover such as an electric motor or the like into an intermittent rotation or an oscillating or swinging output power. Such drive apparatus is suited for intermittently rotating or indexing turntables incorporated in automatic manufacturing machines or other machine tools. Further, the drive apparatus can be advantageously used for feeding intermittently an elongated strip-like blank material to work stations on a step-by-step base. The drive apparatus of this type is generally referred to as the indexing drive apparatus.
2. Description of the Prior Art
In general, a hitherto known indexing drive apparatus comprises an input shaft which is driven continuously by a drive source in a predetermined direction. The continuous rotation of the input shaft is converted into an intermittent rotation or an oscillatory rotation through cooperation of a cam mounted on the input shaft and a cam follower or alternatively through cooperation of a one-way clutch and a brake and transmitted to an output shaft through a gear train. The indexing drive apparatus of this type usually suffers from a serious problem in that the rotation angle or magnitude of the intermittent rotation of the output shaft can not be changed without replacing gears constituting the gear train or the like transmitting elements. Consequently, troublesome procedure is required for the replacement of the gears to a great disadvantage. Further, a frequent change required in the pitch of the intermittent rotation involves a great loss in the overall operation efficiency.
As an attempt to overcome the above difficulty particularly in the field of a sheet material feeding roller apparatus, there has been proposed an arrangement in which an elongated arm integrally combined with the cam follower member is operatively coupled to the output shaft through a connecting rod. A slidable member is mounted on the arm so as to be movable in the axial direction of the arm and one end of the connecting rod is pivotally connected to the slidable member. For example, reference is to be made to Japanese Laid-Open Patent Publication No. 43284/1978. With this arrangement, it is certainly possible to change the magnitude of the intermittent rotation or swing movement of the output shaft by varying the position of the slidable member relative to the arm without requiring replacement of the transmitting elements such as gears. However, the prior art drive apparatus is also disadvantageous in that the adjustment can not be effected without interrupting the operation of the drive apparatus as well as the machines as driven. Additionally, backlash is likely to occur in operation and thus the drive apparatus is not suited for a high speed operation. Further, the prior art driving apparatus can not assure an indexing operation with a high accuracy.